The present invention generally relates to beverage can ends, and more specifically metallic beverage can ends used for interconnection to a beverage can body.
Beverage containers and more specifically metallic beverage cans are typically manufactured by interconnecting a beverage can end on a beverage container body. In some applications, two ends may be interconnected on a top side and a bottom side of a can body. More frequently, however, a beverage can end is interconnected on a top end of a beverage can body which is drawn and pressed from a flat sheet of blank material such as aluminum. Due to the potentially high internal pressures generated by carbonated beverages, both the beverage can body and the beverage can end are typically required to sustain internal pressures exceeding 90 psi without catastrophic and permanent deformation. Further, depending on various environmental conditions such as heat, over fill, high CO2 content, and vibration, the internal pressure in a beverage can may exceed internal pressures approaching 100 psi.
Thus, beverage can ends must be durable to withstand high internal pressures, yet manufactured with extremely thin materials such as aluminum to decrease the overall cost of the manufacturing process and weight of the finished product. Accordingly, there exists a significant need for a durable beverage can end which can withstand the high internal pressures created by carbonated beverages, and the external forces applied during shipping, yet which is made from durable, lightweight and extremely thin metallic materials. The following patent application describes an improved beverage can end which is adapted for interconnection to a beverage can body and which has an improved countersink, central panel area and unit depth which significantly saves material costs, yet can withstand significant internal pressures.
Thus, in one aspect of the present invention, a beverage can end is provided which can withstand significant internal pressures approaching 100 psi and yet saves between 3% and 15% of the material costs associated with manufacturing a typical beverage can end.
In another aspect of the present invention, a beverage can end is provided which is manufactured with conventional manufacturing equipment and thus eliminates the need for expensive new punches and presses required to make the beverage can end. Thus, existing and well known manufacturing equipment and processes can be implemented to quickly and effectively initiate the production of an improved beverage can end in an existing manufacturing facility.
In another aspect of the present invention, a method for forming a beverage can end is provided, and which results in a can end with a countersink radius of no greater than 0.015 inches. More specifically, the method for manufacturing generally comprises a two-step process, wherein a conventional can end xe2x80x9cpre-shellxe2x80x9d is first formed and then captured between two opposing tools, where a clamping function is then performed prior to placing the beverage can countersink in compression. The reforming tool positioned on the underside of the shell contains the desired panel diameter, panel radius, wall type, and outer preferred geometric dimensions as necessary. The pre-shell is then pushed into the reforming tool, which forces the countersink area against the panel tool and rolling up the panel, thus taking the panel tool shape and wrapping the lower radius tight against the panel tool. Preferably, the reforming of the pre-shell is accomplished without using a punch directed downward into the countersink area.
It is another aspect of the present invention to provide a beverage can end which saves material costs by reducing the size of the blank material as opposed to utilizing thinner materials which are susceptible to failure. Thus, the integrity and strength of the beverage can end is not compromised, while material costs are significantly reduced as a result of the blank reduction.
It is a further object of the present invention to provide a beverage can end which utilizes reduced thickness metallic materials to save additional costs, yet provide sufficient strength based on the aluminum alloy properties provided therein.
It is a further aspect of the present invention to provide a beverage can end with an upper chuck wall oriented at a first chuck wall angle xcex81 and a lower chuck wall oriented at a lower chuck wall angle xcex82. Further, the unit depth between an uppermost portion of a circular end wall and a lowermost portion of a countersink is between about 0.215 and 0.225 inches.
Thus, in one aspect of the present invention, a metallic beverage can end is provided which comprises:
a circular end wall adapted for interconnection to a side wall of a beverage can;
an upper chuck wall interconnected to said circular end wall and extending downwardly at an upper chuck wall angle xcex81 of between about 25-35 degrees as measured from a vertical plane;
a lower chuck wall integrally interconnected to said upper chuck wall and extending downwardly at an upper chuck wall angle of between about 18-32 degrees as measured from a vertical plane.
a countersink interconnected to a lower portion of said lower chuck wall and a lower portion of an inner panel wall and having a radius of curvature less than about 0.015 inches;
said inner panel wall extending upwardly at an angle xcfx861 of between about 0 and 8 degrees from a substantially vertical plane; and
a central panel interconnected to an upper end of said inner panel wall and raised above said countersink.